1. Field
Exemplary embodiments relate to 3-dimensional (3D) image acquisition apparatuses and methods of driving the same. In particular, exemplary embodiments relate, to 3D image acquisition apparatuses and methods of driving the same, which may improve depth resolution and reduce power consumption.
2. Description of the Related Art
Research has been increasing in the fields of 3-dimensional (3D) cameras, motion sensors, and laser radars (LADARs) capable of acquiring distance information to an object. In particular, research has been occurring in the field of 3D content because of increased demand for 3D display apparatuses capable of displaying an image having a sense of depth. Accordingly, research is being conducted into various 3D image acquisition apparatuses that enable users to produce 3D content.
A binocular stereo vision method, which uses two cameras or a triangulation method using structured light and a camera, may be used to obtain depth information about the distances between a 3D image acquisition apparatus and the surfaces of an object. However, in this method, it is difficult to obtain accurate depth information because the accuracy of depth information depends on the surface state of an object and degrades rapidly as the distance to the object increases.
In order to solve this problem, a time-of-flight (TOF) method may be used. TOF technology is a method of measuring the flight time of light until the light reflected from an object is received by a light-receiving unit after illumination light is irradiated onto the object. According to the TOF technology, an illumination optical system, including a light-emitting diode (LED) or a laser diode (LD), is used to project light of a certain wavelength (e.g., 850 nm near-infrared ray) onto an object, and light of the same wavelength reflected from the object is received by a light-receiving unit. Then, a series of processing operations, such as modulation of the received light by an optical shutter having a known gain waveform, are performed to extract depth information. Various TOF technologies have been introduced according to the series of optical processing operations.
In a related art, a 3D image acquisition apparatus employing a TOF technology includes an illumination optical system for emitting illumination light and an imaging optical system for acquiring an image of an object in order to obtain depth information. Further, the imaging optical system may include a color image sensor for generating a general color image by detecting visible light reflected from the object, an optical shutter for modulating the illumination light reflected from the object with a predetermined gain waveform, and a gray-scale image sensor for generating a depth image having depth information by detecting the modulated illumination light.